Pressure Controlled Surface Roughness of SiC Plasma Etching

Abstract

The effects of pressure on the surface roughness of silicon carbide (SiC) film were investigated with variations in other process parameters, including radio frequency source power, bias power, O2 fraction and gap. The SiC films were etched in a C2F6 inductively coupled plasma. The surface roughness, measured by atomic force microscopy, was examined in three particular situations: generated at minimum parameter level (case 1), at high source power (case 2); and at high bias power (case 3). For all variations in the process parameters except the O2 variation, smoother surfaces were observed at lower pressures in all cases. Both surface roughness and dc bias due to the pressure variation were highly correlated in case 1. In case 3, they were inversely related. It is noticeable that in cases 1 and 2 the surface roughness was little affected by the pressure, particularly at high bias power. This feature can be used not only for tight control of surface roughness, but for optimising other etch outputs.